What is the classification of most stars on the h-r diagram?

The correct answer is main sequence stars.

Explanation:

The H-R diagram refers to the graphical apparatus, which are used by the astronomers to categorize stars on the basis of their spectral type, luminosity, stage of evolution, color, and temperature. The classification of the majority of the stars on the H-R diagram is the main sequence stars.  

Approximately 90 % of the stars found in the universe, comprising the Sun refers to the main sequence stars. These stars can vary from about the tenth of the Sun's mass to about 200 times.  

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products